Caffeine as a contaminant of periphyton: ecological changes and impacts on primary producers.

Every day, tons of caffeine is consumed by humans in beverages, medications or supplements, and a significant amount of this stimulant is released in domestic sewage. Once in aquatic environments caffeine interacts directly with the periphytic community, which is responsible for a significant part of primary production in aquatic ecosystems. However, the effects of exposure to caffeine are mostly unknown for both the periphyton and their predators. Aiming to comprehend the interaction between caffeine and the periphytic community, ecotoxicological experiments were performed by exposing a periphytic biofilm cultivated in the laboratory to different concentrations of caffeine, following concentrations found in domestic sewers. The impact of exposure to this contaminant was observed on the structure of the community through taxonomic evaluation, as well a set of physiological variables linked to primary production. After exposure to the highest caffeine concentration (300 µg L-1), the density of the genus Scenedesmus was severely affected, leading to an increase in cyanobacteria and diatoms. Both richness and diversity decreased after exposure, and there was lower photosynthetic activity, with light saturation point changing from 186 µmol m-2 s-1 in the control treatment to 108 µmol m-2 s-1 after exposure. Caffeine accumulation within the biofilm was also observed during the first 24 h, in the concentration of 0.14 µg /cm².

Genetic Diversity and Structure of Populations of Annona crassiflora Mart. of Brazilian Savanna and Its Association with Chemical Variability.

Annona crassiflora Mart. is a native tree from Brazilian savanna. Isoquinoline alkaloids are characteristic of species of Annonaceae. This work aimed to assess the magnitude of genetic diversity among different populations of A. crassiflora using AFLP markers, and verify the existence of any correlation between the AFLP data and previous reported alkaloid composition. A. crassiflora from eight populations in the states of São Paulo, Goiás, Minas Gerais, and Distrito Federal were analyzed. The data suggest a low, moderate, and high level of genetic diversity from different populations of A. crassiflora. Concentration of alkaloids was significantly correlated with AFLP data, suggesting interaction between chemical and molecular markers in A. crassiflora. The data of association between the chemical and genetic differentiation of A. crassiflora may be useful to establish cultivation areas allowing the definition of strategies to preserve their genetic diversity with an interest in specific chemotypes for genetic improvement programs focused on sustainable utilization of this specie.

Cuticle structure and chemical composition of waxes in Phaeoceros laevis (L.) Prosk (Notothyladaceae, Anthocerotophyta).

The development of a hydrophobic cuticle covering the epidermis was a crucial evolutionary novelty ensuring the establishment of land plants. However, there is little information about its structure and chemical composition, as well as its functional implications in avascular lineages such as Anthocerotophyta. The main goal of the present study was to compare the gametophyte and sporophyte cuticles of Phaeoceros laevis. Semithin sections were analyzed through light microscopy (LM), cuticle structure was evaluated by transmission electron microscopy (TEM) and epicuticular wax morphology was analyzed by scanning electron microscopy (SEM). Total waxes were analyzed by CG/MS, and the components were identified based on the mass spectra. A thin lipophilic layer was detected on the sporophyte surface, structured as a stratified cuticular layer, similar to the well-known structure described for vascular plants. On the other hand, the gametophyte cuticle was observed only with TEM as a thin osmiophilic layer. SEM analyses showed a film-type wax on the surface of both life phases. The wax layer was eight-fold thicker on the sporophyte (0.8 µg cm-2) than on gametophyte (0.1 µg cm-2). Possible mechanical and/or drought protection are discussed. Fatty acids, primary alcohols, and steroids were identified in both life phases, while the kauren-16-ene diterpene (3%) was detected only on the sporophyte. Although no alkanes were detected in P. laevis, our findings unveil great similarity of the sporophyte cuticle of this hornwort species with the general data described for vascular plants, reinforcing the conservative condition of this character and supporting the previous idea that the biosynthetic machinery involved in the synthesis of wax compounds is conserved since the ancestor of land plants.

Antioxidant Activities of Commiphora leptophloeos (Mart.) J. B. Gillett) (Burseraceae) Leaf Extracts Using In Vitro and In Vivo Assays.

Commiphora leptophloeos is widely used in folk medicine without any scientific basis. Considering this, the aim of this study was to evaluate the chemical profile and the antioxidant activity of C. leptophloeos leaf extracts using in vitro and in vivo assays. Six extracts were obtained from fresh leaves using a serial extraction (nonpolar to polar solvents). These extracts were first evaluated with the presence of phytochemical compounds using the methods thin layer chromatography (TLC), ultrahigh performance liquid chromatography (UHPLC-DAD), and high performance liquid chromatography, both with diode array detection (HPLC-DAD). Based on the compounds identified, it was used some bioinformatics tools in order to identify possible pathway and gene targets. After that, the antioxidant capacity from these extracts was analysed by in vitro assays and in vivo assays using Caenorhabditis elegans model. Phytochemical analyses showed the presence of polyphenols, such as rutin, vitexin, and quercetin diglycosides in all extracts, especially in ethanol extract (EE) and methanol extract (EM). Bioinformatics analysis showed these polyphenols linked to antioxidant pathways. Furthermore, EE and EM displayed a high antioxidant capacity in DPPH and superoxide radical scavenging assays. They also had no effect on cell viability for 3T3 nontumour cell. However, for B16-F10 tumour cell lines, these extracts had toxicity effect. In vivo assays using C. elegans N2 showed that EE was not toxic, and it did not affect its viability nor its development. Besides, EE increased worm survival under oxidative stress and reduced intracellular reactive oxygen species (ROS) levels by 50%. Thus, C. leptophloeos EE displayed an important in vitro and in vivo antioxidant capacity. The EE extract has polyphenols, suggesting that these compounds may be responsible for a myriad of biological activities having this potential to be used in various biotechnological applications.

Signaling pathway played by salicylic acid, gentisic acid, nitric oxide, polyamines and non-enzymatic antioxidants in compatible and incompatible Solanum-tomato mottle mosaic virus interactions.

Plants are exposed to a vast array of pathogens. The interaction between them may be classified in compatible and incompatible. Polyamines (PAs) are involved in defense responses, as well as salicylic acid (SA), gentisic acid (GA) and nitric oxide (NO), which can increase the content of reactive oxygen species (ROS), creating a harsh environment to the pathogen. ROS can also damage the host cell and they can be controlled by ascorbate and glutathione. Among phytopathogens, one of the major threats to tomato crops is tomato mottle mosaic virus (ToMMV). Resistance against this virus probably involves the Tm-22 gene. This work aimed to analyze signaling and antioxidant molecules in the defense response against ToMMV in Solanum pimpinellifolium and in S. lycopersicum 'VFNT'. In S. pimpinellifolium plants inoculated with ToMMV, an increase in NO, SA, GA, ascorbate and oxidized glutathione and a decrease in the content of PAs were observed. Characteristic symptoms of diseased plants and high absorbance values in PTA-ELISA indicated a compatible interaction. In VFNT-inoculated plants, less significant differences were noticed. Symptoms and viral concentration were not detected, indicating an incompatible interaction, possibly associated with the effector-triggered immunity (ETI) response.

Coccoloba alnifolia Leaf Extract as a Potential Antioxidant Molecule Using In Vitro and In Vivo Assays.

The genus Coccoloba is widely used in traditional folk medicine, but few scientific data exist for this genus. The goal of this study was to characterise the chemical composition and antioxidant activities of C. alnifolia leaf extracts using in vitro and in vivo assays. Six extracts were obtained: hexane (HE), chloroform (CE), ethanol (EE), methanol (ME), water end extract (WEE), and water extract (WE). Thin-layer chromatography (TLC) analysis showed the presence of phenols, saponins, terpenes, and flavonoids. In vitro assays demonstrated substantial antioxidant potential, especially for polar extracts (EE, ME, WEE, and WE). Moreover, no toxic effects were observed on mammalian cell lines for most of the extracts at the concentrations evaluated. The nematode Caenorhabditis elegans was also used as an in vivo model for testing antioxidant potential. The EE and WE were chosen, based on previously obtained results. It was observed that neither the EE nor the WE had any toxic effect on C. elegans development. Additionally, the antioxidant potential was evaluated using tert-butyl hydroperoxide as a stressor agent. The EE increased the life span of C. elegans by 28% compared to that of the control, and the WE increased the range to 39.2-41.3%. High-performance liquid chromatography (HPLC-DAD) showed the presence of gallic acid, p-coumaric acid, and vitexin in the WE. Therefore, in vitro and in vivo data demonstrated the antioxidant potential of C. alnifolia extracts and their possible biotechnological applications.